Project Hyper Miler Jetta MKIV TDI Part 4, Upgrading the Turbo with Garrett

Project Hyper-Miler Jetta MKIV TDI Part 4, Upgrading the Turbo with Garrett

By Colin Clyne

For this 4th installment, the long-lost Project Hypermiler gets some ponies! We install a turbo from Garrett to take care of the hot side, and injectors and a tune from KermaTDI to take care of the cold side!

This revival of project TDI begins with my father buying a 2004 Golf TDI brand new and putting over 300k miles on it before selling it to my little brother. That’s relevant because when I went looking for a commuter in 2014, I went looking for an MK4 TDI, purchasing almost the identical vehicle. And as the readers of MotoIQ all know, nothing is ever good enough stock. I found the MotoIQ project TDI through a search and copied its suspension exactly. In the fall of 2015, an impatient driver decided to pass my wife as she was making a left turn and collided with my Golf, bending the unibody below the A-pillar. The vehicle was subsequently totaled, and I was on the hunt for another. It just so happened that the original owner of Project TDI had just posted his car online, and recognizing it immediately, I pounced on it.

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Here you can see the bent and battered Golf, awaiting its fate on Craigslist. The keen-eyed of you will notice that those are, in fact, Subaru WRX wheels, chosen for their light weight and low cost. I did have to find a guy to mill out the center bores.

 

I’ve done a couple of things to the Jetta since I’ve owned it, mainly in the name of comfort. My wife (the primary driver) said that the car was too bouncy on it’s ST suspension, so when I refreshed the suspension at about 260,000 miles, I removed the ST coilover setup and put on a mild spring/shock combo that was closer to stock (the ST’s handled way better). I also replaced the steering wheel with one from a GTI/GLI.

Here is the sportier wheel! It feels so much better in your hands and was so inexpensive that you really owe it to yourself to do this swap if you have an MK4. Of particular mention is the 9/3 area, and how smooth it is where you hook your thumbs. Its better than the wheels of cars costing 10x as much.

Having heard of TDI owners who have installed just one or two of the three separate modifications that we’re going to cover during this installment, we were curious what each mod would do on its own, so we dyno’d the car to get a baseline, and then dyno’d the car again after each mod.

With a stated 90 HP and 155 FTLB stock (also 18 years and almost 290,000 miles ago), the ALH TDI is no rocket ship, but the 40MPG makes up for it. Here is our baseline run:

 

76 hp and 134 FTLB, not bad once you factor in driveline loss and almost 290,000 miles!

 

We also installed a EGR delete for a short while, here is that less than stellar result… The best pull with the EGR delete resulted in 69.3HP and 119.3FTLB.

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